The prior processes involved for “sighting in” a firearm typically involve the use of a target and live ammunition. While this process is typically satisfactory for the shooter, a considerable amount of time and a degree of expense are involved.
The above “sighting in” process may not be available in certain situations. For example, a hunter may jar the firearm and upset the previous sight adjustments. The hunter may be in a situation where the typical process for “sighting in” the weapon is not possible or advisable. This is especially true in situations where the discharge of the firearm could have a negative effect on hunting situations. Further, access to a proper target range is not always easily available. A need has therefore been realized for some form of sighting device that does not require discharge of live ammunition to at least initially accurately set the targeting sights of the firearm.
In response to the above need, various forms of “bore” sighting devices have been developed. In the distant past, such sighting devices made use of incandescent-type lights. More recent developments, however, have lead to the use of laser sighting arrangements. Of these, numerous units are adapted for insertion at the muzzle end of the firearm. The use of a laser certainly increases the potential for accuracy. However, the mounting of a laser in the muzzle end of a firearm does not necessarily lead to an accurate representation of the path a bullet will travel to a selected spot on a target. A very slight misalignment of the laser beam from this point will result in huge magnification of the error at even relatively short distances.
Others have sought the solution of mounting a laser optical device within the firing chamber of a firearm. One such device is described in U.S. Pat. No. 5,787,631 to Kendall. Another such device is described in U.S. Pat. No. 6,631,580 issued to Davis et. al., which is incorporated herein by this reference.
A need has remained for a firearm bore sight system that will maintain an accurate coaxial relationship with a firearm cartridge-shaped insert so that a light beam will be maintained in a coaxial relationship with a muzzle loader type of firearm bore so a reliable and repeatable identification can be easily and quickly determined. A dot of light, then, at a distance of, say, twenty-five to thirty yards, will reliably indicate that point as being along the axis of the firearm bore. This point can then be used to accurately gage and calibrate the external sighting device for the weapon.
In-line muzzle loader firearms and the configuration thereof present a unique problem in the use of such laser sighting cartridges due to the less than desirable chamber to hold and accurately locate a laser cartridge, and difficulty in placing a bore sight into the same location of the breach each time.
An object of the present invention is to provide a laser based in-line muzzle loader firearm bore sighting system for sighting a muzzle loader with internal threads in the breach.